How To Determine The Efficiency Of A Centrifugal Pump

Aug 03, 2024

1, Several factors affecting the power of centrifugal pump units
The power of a centrifugal pump is the product of mechanical, volumetric, and hydraulic power. The power of a single-stage centrifugal pump set is the product of the pump power and the motor power.
1. The pump's own power is influenced by the foundation. Pumps under the same working conditions may differ in power by more than 15%.
2. The operating conditions of the centrifugal pump are lower than the rated conditions of the pump, resulting in low pump efficiency and high energy consumption.
3. The motor power remains unchanged during operation. Therefore, choosing a high-power motor is crucial.
The impact of mechanical power is mainly related to planning and production quality. After the pump is selected, the impact of later processing is relatively small.
5. Hydraulic loss includes hydraulic friction and local resistance loss. After a certain period of pump operation, it is inevitable to form surface wear on components such as impellers and guide vanes, increase hydraulic loss, and decrease hydraulic power.
6. Pump volume loss, also known as leakage loss, includes three types of leakage loss: impeller sealing ring, inter stage, and axial force balance mechanism. The unevenness of volumetric power is not only related to planning and production, but also to later processing. After a certain period of continuous operation of the pump, due to friction between various components, the gap increases and the volumetric power decreases.
7. Due to blockage of the filter cylinder, intake of pipelines, and other reasons, the centrifugal pump may become idle and run freely.
8. Before starting the pump, employees do not pay attention to the preparation work before starting the centrifugal pump. The fundamental operating procedures such as warm-up pump, disc pump, and infusion pump are not fully implemented, often resulting in pump cavitation, causing high pump noise, vibration, and low pump efficiency.
By understanding the influencing factors of centrifugal pump power, we can know the measures that should be taken to reduce the energy consumption of centrifugal pumps and increase the power of pump units.
1. Replace with a higher power centrifugal pump. When replacing, try to choose a centrifugal pump that is close to the actual operating parameters to ensure that the replaced pump always operates at high efficiency. We conducted a power comparison test before and after replacing the centrifugal pump, and the test showed that replacing the inefficient and high consumption centrifugal pump can improve pump efficiency by about 10%.
2. Use of frequency conversion energy-saving skills. For centrifugal pumps with planning parameters greater than actual operating conditions, after installing variable frequency speed regulation equipment, they continue to operate in the high-efficiency zone.
When selecting a new pump, one should choose a pump produced by a large manufacturer to ensure high power of the centrifugal pump.
4. Regularly organize the filter cylinder, check the pipeline connection, and ensure that the inlet pipeline of the centrifugal pump is unobstructed.
5. Strictly follow the operating procedures of the centrifugal pump. Before starting the pump, the pump should be turned on, the inlet valve should be opened, the outlet valve should be closed, and exhaust should be carried out to check whether the inlet pressure of the pump meets the requirements. Prevent pump cavitation caused by low supply pressure and insufficient flow rate.
6. Regularly conduct pump efficiency testing on centrifugal pumps, and for pump units with low pump efficiency, promptly identify the cause and take corresponding measures to solve it.
In addition, when the centrifugal pump is used to transport slurry flows containing large to small scale materials in the liquid, methods to reduce the wear of the centrifugal pump impeller and increase the centrifugal pump power include:
Spray the liquid tangentially into the vortex chamber to form a vortex, and remove a portion of the liquid from the chamber along the tangential direction;
Inject the mud axially into the chamber, and the vortex separates the large-scale material from the remaining mud and liquid;
Remove the remaining mud and liquid from the chamber along the axial direction and spray them into the inlet of a centrifugal pump;
Using the material extracted from the centrifugal pump as the ejection liquid to form the vortex;
Therefore, the large-scale material moves towards the outer circle of the vortex and is discharged. As a result, medium, small, and large-scale materials and liquids are sprayed into the centrifugal pump, thereby reducing the wear of the impeller and increasing the power of the pump by operating at high speed.